/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.reactive.function.client;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.function.Consumer;

import org.springframework.http.codec.ClientCodecConfigurer;
import org.springframework.http.codec.HttpMessageReader;
import org.springframework.http.codec.HttpMessageWriter;
import org.springframework.util.Assert;

/**
 * Default implementation of {@link ExchangeStrategies.Builder}.
 *
 * @author Arjen Poutsma
 * @since 5.0
 */
class DefaultExchangeStrategiesBuilder implements ExchangeStrategies.Builder {

    private final ClientCodecConfigurer codecConfigurer = ClientCodecConfigurer.create();


    public DefaultExchangeStrategiesBuilder() {
        this.codecConfigurer.registerDefaults(false);
    }

    public void defaultConfiguration() {
        this.codecConfigurer.registerDefaults(true);
    }

    @Override
    public ExchangeStrategies.Builder codecs(Consumer<ClientCodecConfigurer> consumer) {
        Assert.notNull(consumer, "'consumer' must not be null");
        consumer.accept(this.codecConfigurer);
        return this;
    }

    @Override
    public ExchangeStrategies build() {
        return new DefaultExchangeStrategies(this.codecConfigurer.getReaders(),
                this.codecConfigurer.getWriters());
    }


    private static class DefaultExchangeStrategies implements ExchangeStrategies {

        private final List<HttpMessageReader<?>> messageReaders;

        private final List<HttpMessageWriter<?>> messageWriters;

        public DefaultExchangeStrategies(
                List<HttpMessageReader<?>> messageReaders, List<HttpMessageWriter<?>> messageWriters) {

            this.messageReaders = unmodifiableCopy(messageReaders);
            this.messageWriters = unmodifiableCopy(messageWriters);
        }

        private static <T> List<T> unmodifiableCopy(List<? extends T> list) {
            return Collections.unmodifiableList(new ArrayList<>(list));
        }

        @Override
        public List<HttpMessageReader<?>> messageReaders() {
            return this.messageReaders;
        }

        @Override
        public List<HttpMessageWriter<?>> messageWriters() {
            return this.messageWriters;
        }
    }

}
